UAB in Antarctica 2007

Amphipod Traps

During this upcoming season you are likely to be hearing a lot about tiny, shrimp-like animals called amphipods. Maggie’s first journal entry of the season is all about them and their biology.

We are particularly interested in amphipods because our past research at Palmer has led us to believe that they may be very important herbivores in this system. They are very small, often just a few millimeters long, but they are exceptionally abundant in the macroalgal (seaweed) communities along the western Antarctic Peninsula where we work. Former group member Yusheng Huang’s work showed that in some of the algae at Palmer there can be hundreds-of-thousands of amphipods per square meter of bottom. That’s a lot!

We have several scientific questions we will be asking about amphipods and their interactions with the macroalgae and you’ll be hearing about those later. We have several very good ways of catching them for use in experiments. But for a couple of the questions, it occurred to me that it would be useful if we could trap them in order to compare relative numbers of them in different places or times of the day.

So how do you trap amphipods? To get at that I went to the scientific literature and found that another group of scientists in another part of the world had done this using a miniature version of a very standard aquatic animal trap known as a funnel trap.

Funnel traps are used to catch all kinds of things including fish, lobsters, and crabs. Essentially they are some kind of mesh cage with bait inside. There is an entrance that is funnel shaped. Animals start in the wide mouth of the funnel and have to go through the small end to get at the bait. But since to get back out they have to find that one small opening at the bottom of the funnel, many of them do not get out.

I decided that we should make our funnel traps using real laboratory funnels and two-liter plastic laboratory bottles. These would have large windows cut in them covered with, well, window screening. It turns out that the standard window screen mesh we all use in our household windows is just big enough to keep in an amphipod while letting it see and smell the bait from the outside of the trap.

Since time at Palmer is so precious, we spent the time making the traps at UAB and shipped them down to meet us in Antarctica. We are very fortunate in the UAB School of Natural Sciences and Mathematics to have an excellent scientific machine shop operated by Jerry Sewell, a wonderful man who is a previous recipient of the UAB Employee of the Year award. Maggie and I marked where we wanted the windows cut in the bottles, bottle lids, and funnels and Jerry cut them for us using standard and hole saws.

Next, Maggie and I filed the cut edges to smooth them and then assembled the traps. The window screening was cut to the appropriate sizes and then attached to the bottle walls and funnels with duct tape and to the window in the bottle lids with silicon sealant. Finally, the funnels were attached to the bottle bottoms (which Jerry had sawed off) with cable ties.

Marine ecologists often joke that you can’t do field work without duct tape, silicon sealant, and cable ties. So I figure that the amphipod traps we built must be perfect for this! But we’ll see when we get to Palmer Station, and we’ll let you know…